Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), affects approximately two million people in North America. Although various non-specific anti-inflammatory treatment modalities are available, the need remains to develop more effective and specifically targeted therapies for treating IBD. Therefore, the overall objective of the present proposal is to test the effects of systemic and locally targeted over-expression of anti-inflammatory genes to modify the course of IBD by restoring the balance between proinflammatory and anti-inflammatory events. In this context, interleukin-1 (IL-1), and its natural antagonist, the IL-1 receptor antagonist (IL-1ra), may play a key role in controlling acute intestinal inflammation. The investigator has demonstrated that: 1) administration of recombinant IL-1ra (rIL-1ra) is effective in reducing disease severity in an animal model of experimentally induced colitis, 2) endogenously produced IL-1ra is crucial for the regulation of acute intestinal inflammatory responses, and 3) a specific mucosal imbalance of IL-1 and IL-1ra exists in patients with IBD. Using well established animal models of acute and chronic colitides, the specific aims of this research proposal are: 1) To determine the efficacy of systemic over-expression of rIL-1ra by transplanted, genetically-engineered myoblasts. The development of a cellular transplantation system that can stably produce and deliver bioactive rIL-1ra into the systemic circulation represents an important advance in the treatment of IBD. The investigator proposes to use genetically-engineered myoblasts which have the ability to deliver high sustained levels of rIL-ra protein into the circulation of animals with experimentally-induced colitis. 2) To determine the efficacy of local IL-1ra over-expression by retroviral vector-mediated, gene transfer into the intestinal mucosa. The purpose of this specific aim is to test the hypothesis that transduction of gut mucosal cells, by retention enema delivery of a retrovirally-encoded anti-inflammatory gene (IL-1ra), may represent a potential therapeutic modality for the treatment of IBD. Transduction of the gut epithelia and their progenitor stem cells (i.e. crypt cells) would enable local, targeted production of large amounts of rIL-1ra into the intestinal microenvironment of animals with experimentally induced colitis. Accomplishment of these aims will be done by a series of in vitro and in vivo experiments utilizing molecular biology techniques coupled with established animal models of colitides. The ultimate goal of the present investigation is to improve the treatment of IBD by using gene therapy methodologies.